Methods, systems, and computer program products for selectively processing or redirecting signaling connection control part (SCCP) messages

ABSTRACT

The subject matter described herein includes methods, systems, and computer program products for selectively processing or redirecting SCCP messages. According to one method, an SCCP message addressed to an STP and sent route-on-PC-SSN is received at the STP. It is determined whether the SCCP message can be processed locally by the STP. In response to determining that the SCCP message can be processed locally by the STP, the SCCP message is terminated, processed locally, and a response is sent to the message originator. In response to determining that the message cannot be processed locally at the STP, the SCCP message is redirected to a destination.

RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication Ser. No. 60,773,604, filed Feb. 15, 2006; the disclosure ofwhich is incorporated herein by reference in its entirety.

TECHNICAL FIELD

The subject matter described herein relates to processing SCCP messages.More, particularly, the subject matter described herein relates tomethods, systems, and computer program products for selectivelyprocessing or redirecting SCCP messages.

BACKGROUND

In telecommunications networks, it is often desirable to provide newservices to telecommunications subscribers. For example, in mobilecommunications networks, it may be desirable to migrate subscribers fromone protocol, such as Interim Standard 41 (IS-41), to a new protocol,such as Global System for Mobile Communications (GSM) that provides newservices. In such networks, since subscribers may not all be migrated atthe same time, the network may include IS-41 subscribers, GSMsubscribers, IS-41 switches, GSM switches, IS-41 HLRs and GSM HLRs.

In such a network, IS-41 switches may be the legacy switches. It isdesirable to provide the capability for these legacy switches tocorrectly route calls and send signaling messages relating to migratedsubscribers and new GSM subscribers. One method for allowing IS-41switches to correctly route calls and send signaling messages relatingto migrated and new GSM subscribers is to modify the switches to sendsignaling messages route-on-global-title (route-on-GT). In somenetworks, IS-41 switches send signaling messages, such as signalingconnection control part (SCCP) messages,route-on-point-code-subsystem-number (route-on-PC-SSN). Messages thatare sent route-on-PC-SSN are typically addressed to the finaldestination, such as the IS-41 HLR. Messages that are sent route-on-GTare typically addressed to the point code of an intermediate node, suchas an STP, that performs global title translation, determines thedestination for the messages, and routes the messages to thedestination. Modifying IS-41 switches that send messages route-on-PC-SSNto send messages route-on-GT may not be cost effective, especially innetworks where there is a large base of installed switches.

More generally, the problem of modifying switching offices that sendmessages route-on-PC-SSN to send any type of SCCP messages route-on-GTcan be expensive where there is a large base of installed switches.Accordingly, there exists a need for selectively processing orredirecting messages sent route-on-PC-SSN to a destination using anintermediate node, such as an STP. One problem with using an STP toprocess messages that are sent route-on-PC-SSN is that STPs typicallyroute such messages, rather than apply internal processing. Oneexception where STPs apply internal processing to messages sentroute-on-PC-SSN is when an STP includes a number portability database,such as an LNP database. If an STP includes an internal LNP database,the STP terminates and processes all LNP queries that are addressed tothe STP. However, there is no provisioned capability in an LNP-equippedSTP to selectively process some LNP queries that are addressed to theSTP and redirect other LNP queries that are addressed to the STP to adestination.

Accordingly, in light of these difficulties, there exists a need formethods, systems, and computer program products for selectivelyprocessing or redirecting SCCP messages.

SUMMARY

The subject matter described herein includes methods, systems, andcomputer program products for selectively processing or redirecting SCCPmessages. According to one method, an SCCP message addressed to an STPand sent route-on-PC-SSN is received at the STP. It is determinedwhether the SCCP message can be processed locally by the STP. Inresponse to determining that the SCCP message can be processed locallyby the STP, the SCCP message is terminated, processed locally, and aresponse is sent to the message originator. In response to determiningthat the SCCP message cannot be processed locally at the STP, themessage is redirected to a destination.

The subject matter described herein for selectively processing orredirecting SCCP messages can be implemented using a computer programproduct comprising computer executable instructions embodied in acomputer readable medium. Exemplary computer readable media suitable forimplementing the subject matter described herein include chip memorydevices, disk memory devices, programmable logic devices, applicationspecific integrated circuits, and downloadable electrical signals. Inaddition, a computer program product that implements the subject matterdescribed herein can be located on a single device for computingplatform or may be distributed across multiple devices for computingplatforms.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the subject matter described herein will now beexplained with reference to the accompanying drawings of which:

FIG. 1 is a flow chart illustrating an exemplary process for selectivelyprocessing or redirecting SCCP messages according to an embodiment ofthe subject matter described herein;

FIG. 2 is a network diagram illustrating exemplary messages exchangedfor an SCCP message that is processed by an STP according to anembodiment of the subject matter described herein;

FIG. 3 is a network diagram illustrating exemplary messages exchangedbetween network nodes for an SCCP message that is redirected by an STPaccording an embodiment of the subject matter described herein; and

FIG. 4 is a block diagram illustrating an exemplary internalarchitecture for an STP that selectively processes or redirects SCCPmessages according to an embodiment of the subject matter describedherein.

DETAILED DESCRIPTION

The subject matter described herein includes methods, systems, andcomputer program products for selectively processing or redirecting SCCPmessages. The subject matter described herein may be implemented at anode that is located between a network switching system, such as amobile switching center (MSC) or a service switching point (SSP), and adestination node, such as a home location register (HLR) or a servicecontrol point (SCP), that may be configured to process some of the SCCPmessages. In one implementation, the subject described herein may beimplemented in a signal transfer point (STP). FIG. 1 is a flow chartillustrating exemplary steps that may be performed for selectivelyprocessing or redirecting SCCP messages according to an embodiment ofthe subject matter described herein. Referring to FIG. 1, in block 100,an SCCP message addressed to an STP and sent route-on-PC-SSN is receivedat the STP. Referring to the network example illustrated in FIG. 2, anSTP 200 may be located in a network that includes an IS-41 MSC 202, anIS-41 HLR 204, a GSM MSC 206, and a GSM HLR 208. When IS-41 MSC 202receives an initial address message (IAM) message or other message toinitiate a call to a mobile subscriber, IS-41 MSC 202 may send alocation request message to determine the location of the called party.In this implementation, the location request message is sentroute-on-PC-SSN. The location request message is addressed to acapability point code of STP 200. The capability point code is a pointcode that is used by STP 200 to identify SCCP messages that may beprocessed locally at the STP or redirected.

Returning to FIG. 1, in blocks 102 and 104, it is determined whether theSCCP message can be processed locally by the STP. If it is determinedthat the SCCP message can be processed locally, the SCCP message isterminated, processed locally, and a response is sent to the messageoriginator. Returning to FIG. 2, when STP 200 receives the locationrequest message, STP 200 will recognize the message as being addressedto its capability point code for selective SCCP message processing orredirection. In one implementation, STP 200 determines whether it canprocess the SCCP message locally by determining whether the called partyidentified by the location request message has migrated to GSM or not.In this example, it is determined that the subscriber has migrated toGSM. Accordingly, STP 200 formulates a location request return resultmessage indicating that the subscriber has been migrated. STP 200 sendsthe location request return result message to IS-41 MSC 202. IS-41 MSC202 forwards the call to GSM MSC 206 by sending an IAM message to GSMMSC 206. GSM MSC 206 will then issue a send routing information (SRI)message to GSM HLR 208 to determine the location of the called party.Thus, in FIG. 2, STP 200 determines that it can process an SCCP messagelocally, and processes the message.

Returning to FIG. 1, in block 104, if it is determined that the SCCPmessage cannot be processed locally, control proceeds to block 108 wherethe message is redirected to a destination for processing. Referring toFIG. 3, a location request message originates from IS-41 MSC 202 inresponse to an incoming mobile terminated call. The location requestmessage is sent route-on-PC-SSN to the capability point code of STP 200for selective SCCP message processing or redirection. In this example,it is assumed that the called party has not migrated to GSM.Accordingly, STP 200 may determine that it cannot process the querymessage because the subscriber has not migrated. In this case, STP 200may redirect the location request message to IS-41 HLR 204. IS-41 HLR204 may perform a lookup using a subscriber identifier in the locationrequest message and determine the current location of the subscriber.IS-41 HLR 204 may then send a location request return result message toIS-41 MSC 202 via STP 200 indicating the location of the subscriber.

In one exemplary implementation, in order to redirect the received SCCPmessage to IS-41 HLR 204, STP 200 may copy the called party point codefrom the SCCP portion of the message and place the called party pointcode in the MTP routing label of the message. This implementationrequires that the IS-41 MSC 202 insert the point code of the IS-41 HLRin the called party point code field of the SCCP query message. Thus, inthe example illustrated in FIG. 3, STP 200 redirects a message that wassent to it route-on-PC-SSN in response to determining that STP 200cannot process the message.

FIG. 4 is a block diagram illustrating exemplary components of STP 200for selectively processing or redirecting SCCP messages according to anembodiment of the subject matter described herein. Referring to FIG. 4,STP 200 includes a plurality of internal processing modules 400, 402,404, and 406 connected via a counter-rotating, dual ring bus 408. In theillustrated example, the processing modules include a link interfacemodule (LIM) 400 for interfacing with SS7 signaling links, a datacommunications module (DCM) 402 for interfacing with IP signaling links,and database services modules (DSMs) 404 and 406 for performingdatabase-related services, such as selectively processing or redirectingSCCP query messages.

LIM 400 includes a message transfer part (MTP) level one and twofunction 410 for performing SS7 MTP level one and two operations, suchas sequencing, error detection, and error correction of SS7 signalingmessages sent over SS7 signaling links. Gateway screening function 412screens incoming SS7 messages to determine whether to allow the messagesinto the network. Discrimination function 414 screens incoming SS7messages to determine whether the messages require internal processingby STP 200 or whether the messages should be routed. Distributionfunction 416 receives messages identified by discrimination function 414as requiring internal processing by STP 200. Distribution function 416distributes the messages to an internal processing module, such as DSM404 or 406 for internal processing. Routing function 418 routes messagesidentified by discrimination function 414 as requiring routing.

As stated above, normally, messages that are sent to an STProute-on-PC-SSN are routed by a routing function, such as routingfunction 418, to a destination. However, according to the subject matterdescribed herein, SCCP query messages that may require internalprocessing by STP 200 or redirection are addressed to a capability pointcode of STP 200. For such messages, discrimination function 414 mayidentify the messages as requiring internal processing (eitherredirection or local termination) and forward such messages todistribution function 416. Distribution function 416 may then forwardsuch messages to one of DSM cards 404 and 406 for internal processing.

DCM card 402 includes functionality for interfacing with IP signalinglinks, and in particular, for interfacing with IP signaling links thatcarry IP-encapsulated SS7 signaling messages. In the illustratedexample, DCM 402 includes a physical layer function 420, a network layerfunction 422, a transport layer function 424, an adaptation layerfunction 426, and functions 410-418 described with regard to LIM 400.Physical layer function 420 performs OSI physical layer operations, suchas error correction and error detection of messages sent over OSI layerone and two signaling links. In one implementation, physical layerfunction 420 may be implemented using Ethernet. Network layer function422 performs operations, such as network layer routing of signalingmessages. In one implementation, network layer function may beimplemented using Internet protocol. Transport layer function 424performs OSI transport layer functions, such as connection-oriented orstream-oriented transport of messages. Transport layer function may beimplemented using transmission control protocol, user datagram protocol,or stream control transmission protocol. Adaptation layer function 426performs operations for sending and receiving SS7 messages over IPtransport. Adaptation layer function 426 may be implemented using anySigtran adaptation layer protocol, such as SUA, M3UA, M2PA, or othersuitable protocol. Functions 410-418 may perform the same operations asthe correspondingly numbered functions described with regard to LIM 400.Hence, a description thereof will not be repeated herein.

It should be noted that the subject matter described herein forselectively processing or redirecting SCCP messages is capable ofperforming the processing or redirection for SCCP messages that are sentover IP transport as well as messages that are sent over SS7 transport.Thus, the term “SCCP message” as described herein is not intended to belimited to messages that are sent using SS7 transport across a network.An IP encapsulated SCCP message received by DCM card 402 would beunencapsulated and forwarded to one of DSM cards 404 and 406 forselective processing or redirection, if it is addressed to thecapability point code of STP 200 described above.

DSMs 404 and 406 may be identically provisioned to providedatabase-related and/or other services in a load sharing manner. In theillustrated example, one database-related service that is provided isselective SCCP processing or redirection. Each DSM 404 and 406 may beprovisioned with a service selection function 428 that identifies anSCCP service for an incoming SCCP query message. For messages addressedto the capability point code of selective SCCP message processing orredirection, service selection function 428 may forward such messages toselective SCCP processing/redirection function 430. Selective SCCPprocessing/redirection function 430 may perform a lookup in subscriberdatabase 432 to determine whether an SCCP message can be processedlocally or not. In the migration example described above, messagesdirected to migrated subscribers may be processed locally and messagesthat are directed to non-migrated subscribers may be redirected.Subscriber database 432 may include entries indexed by subscriberidentifiers, such as IMSIs, MSISDN numbers, or directory numbers. Eachentry may include an indication as to whether a subscriber is migrated.Alternatively, database 432 may be populated only with entries formigrated subscribers, eliminating the need to store migration statusindicators in the database entries. Subscriber database 432 may beprovisioned by an external provisioning platform, referred to as Eagle®Provisioning Application Processor (EPAP) 434.

For messages that are processed locally, selective SCCPprocessing/redirection function 430 may terminate such messages,formulate response messages, and forward the response messages to themessage originator. The response messages will be routed by routingfunction 418 to the appropriate LIM or DCM associated with the signalinglink corresponding to the destination point code in the message. Formessages that cannot be processed locally, selected SCCPprocessing/redirection function 430 may extract the SCCP called partypoint code from such messages and replace the MTP destination point codewith the SCCP called party point code. Selective SCCPprocessing/redirection function 430 may forward such messages to routingfunction 418. Routing function 418 may route such messages to the LIM orDCM associated with the destination point code in the message.

Although the examples described above relate to selectively processingor redirecting SCCP messages relating to mobility management in anetwork that allows subscriber migration between mobile signalingprotocols, the subject matter described herein is not limited to theseexamples. For example, the methods and systems described above forselectively processing or redirecting SCCP messages can be used toprocess or redirect any type of SCCP message that is sentroute-on-PC-SSN. Examples of other SCCP messages that may be selectivelyprocessed or redirected include mobile subscriber registration messagesthat require G-FLEX processing at the STP. As used herein, the term“G-FLEX processing” refers to processing at the STP in order todetermine an HLR to which a mobile subscriber location managementmessage should be routed. Typically, G-FLEX queries are sentroute-on-GT. The subject matter described herein allows such messages tobe sent to a point code of an STP and route-on-PC-SSN.

It will be understood that various details of the presently disclosedsubject matter may be changed without departing from the scope of thepresently disclosed subject matter. Furthermore, the foregoingdescription is for the purpose of illustration only, and not for thepurpose of limitation.

1. A method for selectively processing or redirecting signalingconnection control part (SCCP) messages, the method comprising:receiving, at a signal transfer point, an SCCP message addressed to thesignal transfer point and sent route-on-point-code-subsystem-number(route-on-PC-SSN); determining whether the query message can beprocessed locally by the STP; in response to determining that the SCCPmessage can be processed locally by the STP, processing the SCCP messagelocally at the STP and sending a response to an originator of the querymessage; and in response to determining that the SCCP message cannot beprocessed locally at the STP, redirecting the signaling message from theSTP to a destination.
 2. The method of claim 1 wherein the SCCPcomprises a mobility management message in a network that supportsmobile subscriber migration between mobile signaling protocols.
 3. Themethod of claim 2 wherein determining whether the SCCP message can beprocessed locally by the STP includes determining whether a subscriberassociated with the query message has migrated or not migrated betweenthe mobile signaling protocols.
 4. The method of claim 3 wherecomprising determining that the SCCP message can be processed locally atthe STP in response to determining that the subscriber has migratedbetween the mobile signaling protocols.
 5. The method of claim 3comprising determining that the SCCP message cannot be processed at theSTP in response to determining that the subscriber has not migratedbetween the mobile signaling protocols.
 6. The method of claim 1 whereinredirecting the SCCP message to a destination includes copying an SCCPcalled party point code into a message transfer part (MTP) routing labelof the message and routing the query message to a destinationcorresponding to the copied point code.
 7. The method of claim 6 whereinrouting the SCCP message to a destination includes routing the messageto a home location register (HLR).
 8. The method of claim 1 wherein theSCCP message comprises a message requiring G-FLEX processing.
 9. Asystem for selectively processing or routing signaling connectioncontrol part (SCCP) messages, the system comprising: a signal transferpoint including: an interface module for receiving SCCP messagesaddressed to a point code of the STP and sentroute-on-point-code-subsystem-number (route-on-PC-SSN) and foridentifying the SCCP messages as requiring at least some internalprocessing by the STP; a services module for receiving the SCCP messagesthat are identified as requiring at least some internal processing bythe STP, for determining whether each of the SCCP messages can beprocessed locally by the STP, for messages identified as being able tobe processed locally, for terminating and processing the query messageslocally, and for messages identified as not being able to be processedlocally by the STP, for redirecting such messages to a destination. 10.The system of claim 9 wherein the services module is adapted toselectively process or redirect mobility management messages in anetwork allowing subscriber migration between mobile signalingprotocols.
 11. The system of claim 10 wherein the services module isadapted to determine whether subscribers are migrated or non-migrated.12. The system of claim 11 wherein the services module is adapted toprocess and terminate mobility management messages directed to migratedsubscribers.
 13. The system of claim 10 wherein the services module isadapted to redirect mobility management messages directed tonon-migrated subscribers.
 14. The system of claim 13 wherein, inredirecting the mobility management messages, the services module isadapted to copy an SCCP called party point code in each message to amessage transfer part (MTP) routing label of each message.
 15. Thesystem of claim 13 wherein the services module is adapted to route theredirected SCCP messages to an HLR.
 16. The system of claim 13 whereinat least some of the SCCP messages comprises messages requiring G-FLEXprocessing.
 17. A computer program product comprisingcomputer-executable instructions embodied in a computer readable mediumfor performing steps comprising: receiving, at a signal transfer point,an SCCP message addressed to the signal transfer point and sentroute-on-point-code-subsystem-number (route-on-PC-SSN); determiningwhether the SCCP message can be processed locally by the STP; inresponse to determining that the SCCP message can be processed locallyby the STP, processing the query message locally at the STP and sendinga response to an originator of the query message; and in response todetermining that the SCCP message cannot be processed locally at theSTP, redirecting the signaling message from the STP to a destination.